There are a variety of locks; nevertheless the locks are generally classified, on the basis of their construction, into the combination locks and the key locks, which have both advantages and disadvantages. In a way, the popular combination padlock is the better of the combination locks and the key locks. However, the conventional combination padlock has shortcomings, which are expounded explicitly hereinafter.
The cost of making the conventional combination padlock is relatively high in view of the fact that the construction of the conventional combination padlock is complicated and that the quality control of the conventional combination padlock cannot be carried out effectively and economically.
The shackle of the conventional combination padlock can be pulled out accidentally at the time when the shackle is not arrested and retained by all dial sleeves. In addition, there are many gaps in the housing of the padlock in which the dial and other component parts are housed. Such gaps can be used by an unauthorized person to unlock the combination padlock with a device.
The locking and the unlocking mechanisms of the conventional combination padlock involve a number of frictional contacts between the shackle and each of the dial sleeves. As a result, the operation of the conventional combination padlock is painfully slow.
The unlocking mechanism of the conventional combination padlock is inefficient on the grounds that the working of the shackle is not assisted by a spring.